Monarch 3 trial success for abemaciclib + an aromatase inhibitor to treat HR+ human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer.- Eli Lilly

Eli Lilly and Company announced that following a pre-planned interim analysis for MONARCH 3, the trial met its primary endpoint of demonstrating statistically significant improvement in progression-free survival (PFS). In addition, improvement was shown in a key secondary endpoint of objective response rate (ORR). The Phase III study evaluated abemaciclib, a cyclin-dependent kinase (CDK)4 and CDK6 inhibitor, in combination with an aromatase inhibitor (letrozole or anastrozole) compared to treatment with an aromatase inhibitor alone in women with hormone-receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer. Detailed efficacy and safety results will be presented at a medical meeting in the second half of the year.

The global Phase III, double-blind, placebo-controlled study was designed to evaluate the efficacy and safety of abemaciclib in combination with an aromatase inhibitor as initial endocrine-based therapy for postmenopausal women with advanced (locoregionally recurrent or metastatic) breast cancer who have had no prior systemic treatment for advanced disease. A total of 493 patients were randomized to receive 150 mg of abemaciclib or placebo orally twice a day without interruption, given in combination with either 1 mg of anastrozole or 2.5 mg of letrozole once daily until disease progression or unacceptable toxicity. The primary endpoint of the study was PFS, with key secondary endpoints of ORR, overall survival and safety. The adverse events were generally consistent with previous studies of abemaciclib, with the most common adverse events being diarrhea, neutropenia, fatigue, and nausea.

Following this MONARCH 3 interim analysis, Lilly intends to begin global submissions of these results in the third quarter of 2017. In addition, Lilly intends to initiate MONARCH 1 and MONARCH 2 submissions beginning in the second quarter of 2017. Other MONARCH trials currently underway include: monarcHER, which is evaluating abemaciclib plus trastuzumab (with or without fulvestrant) in women with HR+, HER2+ locally advanced or metastatic breast cancer, and MONARCH plus, a Phase III study of abemaciclib in combination with endocrine therapies to support registration in China. In addition, Lilly has an ongoing Phase III trial evaluating abemaciclib in lung cancer. Lilly is also evaluating abemaciclib in patients with brain metastases, as well as in patients with pancreatic cancer.